有源箝位同步整流正激变换器的优化设计

Improved Design of Active Clamp Synchronous Rectification Forward Converter

目前电源技术的发展趋势为高频、高效率、高密度。介绍了专为有源箝位变换器设计的芯片UCC2897以及实现ZVS有源箝位的工作原理。同时,详细介绍了一款18～36V输入、5V/50W输出,工作频率为300kHz,基于UCC2897的有源箝位同步整流DC/DC变换器的电路设计,并对关键器件进行损耗分析,最后进行了实验验证。结果表明,该变换器可以很好地实现主辅开关管的ZVS开通,满载效率可达90%。

Now the development of the power supply trends to high frequency,high efficiency and high density.UCC2897 and operation principle of active clamp forward converter to achieve ZVS are mainly introduced.The design process of active clamp synchronous rectification forward DC/DC converter based on UCC2897 with 18～36 V input,5 V/50 W output and 300 kHz frequency are introduced and verified,so as loss analysis of key devices.The experimental results show that the main and auxiliary switchs used in the new converter can achieve ZVS,and the efficiency can achieve 90%,in line with the development trend of power supply technology.